The present invention relates to the testing of printing inks, and more particularly to a portable fluid ink tack tester for rapidly, conveniently and accurately measuring ink tack on printing presses at any time and any location.
Prior art fluid ink tack testers have for many years used the force necessary to split a film of ink as a suitable measure for the tack of the ink sample. Unfortunately, however, such devices are basically stationary in nature, in the sense that they are operated in a single location and the ink sample is brought to them. Not only is this inconvenient, but since the characteristics of many inks change rapidly when exposed to air, care and speed must be observed to obtain good results.
As a consequence, prior art devices have been proposed which are permanently mounted directly on the printing press to provide an automatic and continuous indication of the tack of the printing ink. Unfortunately, this requires that a discrete tack tester be provided for each inking couple in each printing tower. Not only does this multiply the cost several times over that of a single tester, but there can be physical problems in finding a suitable location and adequate space for these testers, where they are accessible to the machine operator.
A need therefore remains for an inexpensive, reliable, and rapidly operating portable instrument which can be conveniently carried to each inking unit, and will rapidly and accurately test the tack of the ink thereon before it can undergo significant change. Preferably, such a unit should be capable of being hand held and brought directly into contact with inked roll, and then immediately operated to give an indication of the tack of the ink.